#include <iostream>
#include <math.h>

extern const int cpu_number=16;
const double pi=acos(-1.0);
int main()
{   int a=12;
    std::cout<<a<<std::endl;
    int *const p=&a;
    *p=13;
    std::cout<<a<<std::endl;
    int &m=a;
    m=14;
    std::cout<<a<<std::endl;
    std::cout<<cpu_number<<std::endl;
    std::cout<<pi<<std::endl;
    
}